Method of making phonograph-records.



T. A. EDISON.

METHOD 0F MAKING PHONOGRAPH RECORDS. APPLICATION FILED Aue.27, I9I4.

LMGAIA Patented July 13, 1915.

I 2 ./{WfW/MM FFIE.

TO NEW JERSEY PATENT COMPANY, 0F WEST ORANGE, NEW

TION 0F NEW JERSEY.

JERSEY, A CORPORA- METHOD OF MAKING PHONOGBAPH-RECORDS.

i ,recata Speciication of Letters Patent.

Patented July 13, 1915.

Original application filed January 20, 1912, Serial No. 672,397. Divided and this application filed August 27, 1914. Serial No. 858,799.

To all @chomtmay concern:

Be it known that I, THoMAs A. EDISON, a citizen of the United States, and a resident of Llewellyn Park, West Orange, in the county of Essex andState of New Jersey,

have invented certain new and useful Improvements iiil Methods of Making Phonograph-Records, of which the following is a description. p

My invention relates to methods of making phonograph records having a surface of wear resisting material, such as Celluloid, this application being a division of my application Serial No. 672,397 filed January 20, 1912 and entitled Phonograph records.

The object' of my invention is to provide. 4 a record of the type referred to permitting A` tional view of a cylindrical sound record,

the reproduction of the sound record formed thereon with distinctness, loudness and purity. It has been common to provide records with surface films or veneers of hard materials such-as Celluloid; but the reproduction from these records has usually been accompanied by harsh unpleasant scratchyv sounds which I have discovered to be due to the fact that the record surface is hard and unyielding sol that the reprodueer strikes the bottom of the record groove with a more or less sharp blow. In order to overcome thisandfother objections and atthe' same time provide a wear resisting surface for the record, Iv construct my improved record of a flexible or yielding surface film or veneer of hard material, such as a thin sheet of Celluloid, and provide a resilient or yielding backing therefor, this backing being in my preferred construction formed of a base of Hard material, such as plaster of Paris, and a. thin film or layer of resilient material such as rubber, intermediate said surface veneer-and base. The resilient mae terial shouldfb'e a substance, such, for exam? ple, as rubber, which yields but is not liable to permanentdeformation under the 'pressure of the' reproducer stylus. iency'of the intermediate film' or layer permits a slight flexing or yielding' 0f the surface film or veneer under the reproducer so that the sharp-'blowsof the reproducer are cushioned andthe harsh noises above referred to eliminated; while the rigidity of The resil-A lthe base prevents a diminution of the amplitude of the sound waves as reproduced,

'so that the sound waves on the record surface are transmitted with full amplitude to the reproducer diaphragm. It is understood that the intermediate film above re-v ferred to yields only suiiiciently to permit` the cushioning of the stylus so as to elimi nate the harsh sounds referred to above.

Other objects of my invention will appear embodying my invention; and Fig. 2 represents a similar view of a disk sound record embodying my invention.

Referring tothe drawings and more Vpar-l ticularly to Fig. 1, the reference numeral 1- indicates a-cylinder of hard' material such as Celluloid, this cylinder being formed at its ends with inwardly directed flanges 2 and 3. The cylinder l is vcovered on the in# terior thereof with a thin coating 4 of reu silient material, such as rubber, this coating being preferablyl applied by rotating the cylinder 1 and applying a solution of the resilient material, as with a brush, to the interior or'bore of the cylinder. When rubber is used, I lprefer to employ a Asolution of the same in benzol. After the layer or film 4 has been allowed to dry, I form on the interior thereof, as by casting, a backing 5 of hard unyielding material, such as plaster of Paris. In carrying out the casting operation in practice, I place within the coated cylinder 1l a core having a recess or groove opening at one end and in the lateral surface of the core, and pour the material to be cast into this recess or groove, from which it is led into the annular space between the core and the film 4. The base 5 is dried by placing the record within an oven, after 4 which the record may be reamed and otherwise suitably finished. In practice,l the core is preferably slightly withdrawn before the base 5 is dried so as to prevent the formatioirof an objectionable projection within the bore of the record at the place where the recess in the mold is located. The flanges 2 and ,3 are preferably of `slightly greater Idiameter .than the corresponding ends of the bore of the base 5, the record beingsupportedwhen in place on thevphonograph mandrel entirely bythe base 5. The record impression is preferably formed on the surface of the celluloid film l prior to Athe application of the yielding film and the base thereto.

In order to produce best results, the film or veneer l should be sufficiently thin to be flexible or yielding and the film 4 should be of such a thickness as to cushion the sharp sudden movements of the reproducer stylus which produce the harsh sounds referred to above without causing such a Hexing or yielding yof the surface veneer asto appreciably decrease the volume of sound emitted during the reproducing of the rec ord. VIn practice, I have found that a suitablethickness for the `Celluloid surface film is about .018 y Aand that a suitable thick-V ness for the intermediate film of rubber `is about .0015.

Referring to Fig. 2, the numerals 1 4 and 5 indicate respectively the hard surface Afilm or veneer, yielding intermediate film,

and hard base of a disk record constructed in accordance with my invention. .The veneer 1 and film 2, as in the form of my invention describedl above are preferably formed respectively of celluloid andrubber. For the disk sound records, however, I prefer to provide a base not only of considerable hardness but also of considerable toughness and capable ofadhering firmly to the intermediate film. Suitable materials for such a base are hard rubber or the phenolic condensation products which form the sub-v I have found in practice that the employment of the yielding intermediate film referred to above not only improves the quali ity of the record but also decreases the wea r of the stylus on the record and thereby materially increases the life thereof, .the hard unyielding base ness and distinctness o the record.

Various materials other thanfjt i ose specified above may be used by me an numerous The celluloid for the disk record fpreserving the l/oude other modifications may be made within the scope of my invention. y What I claim as new and desire to protect byLetters Patent is as follows:

1. The process of making record tablets which comprises forming a surface veneer of hard material, applying to the back of said veneer a coating of resilient material, and a'llowing the same to dry, substantially as described.

,2. The process of making'record tablets which comprises forming a Celluloid surface veneer, applying to the back of said veneer a coating of resilient material, .and allowing'v4 the same to dry, substantially as described. v

3. The process of making record tablets which. comprises forming a thin surface veneer of hard material, applying to the back of said veneer a coating of rubber, and allowing the same to dry, substantially as described.

4. yThe process of making record tablets which comprises forming a thin celluloid surface veneer, applying to the back of said veneer a coating of rubber, and allowing the same to dry, substantially as described.

5. .The process of making recordtablets which consists in forming a thin surface veneer ,of hard material, applying to the back of said veneer a coating of resilient material,allowing the said coating to dry, and providing the coated veneer with a base of hard unyielding material, substantially as described.

6. The process of making record tablets which consists in forming a thin surface veneer` of hard material, applying to the back of said veneer a film of resilient material, and casting a hard unyielding base Within the said film, substantially as described.

7. The process 'of making record tabletsv which consists in forming a thin surface veneer of hard material, applying to the Iback of said veneer a coating of resilient material, allowing the said coating to dry, and casting a hard unyielding base within the coated veneer, substantially as described.

8. The process of making record tablets which consists in forming a thin tube of hard material, applyingY to the bore of said tube a coating of resilient material, allowvizo which consists in forming a thin tube of This specification signed and witnessed Celluloid, applying to the base of said tube a this 26th day of August, 1914.

coating of resilient material, allowing the THOS. A. EDISON. said coating to dry, and casting a hard un- Witnesses: yielding base within the coated tube, sub- FREDERICK BACHMANN,

stantially as described. MARY J. LAIDLAW. 

